In the production of media webs, particularly photosensitive film web, devices that employ mechanically coupled rotatable elements are widely used to convey the web of indeterminate length between a variety of processing stations. More particularly, such apparatus will normally guide and move the web through a processing sequence involving developer, fixer, washing, and drying bath stations which tend to expose the conveyance rotatable elements of the apparatus to corrosive materials. With mechanically coupled driven rotatable elements of the type presently used in web conveyance equipment, sensitive mechanical gears that synchronize the rotation of the rotatable elements and some sort of drive means, typically a motor, coupled to the rotatable elements for producing the desired rotation may be interrupted if exposed to harmful and deleterious materials.
Hence, it is well known that one major shortcoming of conventional mechanically coupled rotatable elements is that the excessive exposure of the mechanical elements to various corrosive materials will invariably result in degraded mechanical performance. As a consequence, the equipment, and therefore production, must be frequently interrupted for maintenance and parts replacement.
Moreover, during the processing of photosensitive web, experience indicates that the web will invariably tend to show signs of objectionable wear and abrasion as the performance of conventional mechanically coupled conveyance rotatable elements degrade during extensive and continuous exposure to corrosive materials. Hence, degraded rotatable elements and associated web conveyance elements tend to have an adverse effect on the quality of the costly photosensitive web product.
Another well recognized problem associated with conventional web conveyance equipment is that such equipment does not easily accommodate photosensitive film webs having a variety of thickness. In order to accommodate the processing of such film webs (each having a different thickness) enormous downtime and production cost sacrifices are realized so that required adjustments to a transfer nip separating the mechanically coupled rotatable elements can be made. Thus, photosensitive film web processing equipment that utilizes conventional mechanically coupled rotatable elements as a means of conveying the film web through various processing stations require costly and time consuming maintenance and adjustment.
Therefore, a need persists for a magnetically induced coupling and drive apparatus suitable for conveying photosensitive web materials in corrosive environments without the concerns that the equipment will require excessive and costly maintenance as well as will impart harmful defects to the film web. Moreover, there exists a need for such apparatus and method that easily accommodates adjustments for processing webs of different thickness.